Ajai Garg - Academia.edu (original) (raw)

Papers by Ajai Garg

Indian Journal of Public Health Research & Development

Materials Science and Engineering B Advanced Functional Solid State Materials, May 1, 1999

The effect of net PbO content (obtained by taking into account the amount of excess PbO added and... more The effect of net PbO content (obtained by taking into account the amount of excess PbO added and PbO loss during sintering) on the mechanical and piezoelectric properties of lead zirconate titanate (PZT) ceramics has been studied. The samples were prepared by the solid state route using the morphotropic phase boundary composition Pb(Zr 0.535d Ti 0.465)O 3. Excess PbO was also added to the samples in varying amounts from 0-1.0 wt.%. To vary PbO volatility the samples were sintered with and without a PbO rich atmosphere at 1220°C for 2 h. The resulting Pb content as given by x in Pb 1 + x (Zr 0.535 Ti 0.465)O 3 + x varied from x= −1.7 ×10 − 2 to 1.8 ×10 − 2. The sintered density was found to increase with increasing lead content. The precipitation of the second phase believed to be ZrO 2 is observed for x= −1.7× 10 − 2. The fracture mode changed from intergranular to transgranular with increasing x. The fracture toughness (K IC) and strength are minimum near x =0 and increase with increasing as well as decreasing x. The maximum values of K IC and strength are 1.45 MPa m 1/2 and 90 MPa, respectively, for x =1.8× 10 − 2. The dielectric constant and piezoelectric strain coefficient d 33 increased with x.

Ferroelectrics, 2001

Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the ... more Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the morphotropic phase boundary (MPB) replaced with different amounts of Ce have been prepared according to the formula Pb(Zr0.535-δTi0.465Ceδ)O3 with δ between 0.0 and 0.05. The sintering has been carried out without any atmosphere powder so as to provide a Pb deficient atmosphere and facilitate the formation of second phase particles. The loss of weight during sintering increases sharply with the initial addition of CeO2 upto δ = 0.0025. The sintered density decreases with the initial addition of CeO2 and then increases, reaching a maximum value at δ = 0.006. The x-ray and weight loss data point to Ce going to the A site in samples with low CeO2. Particles of a CeO2 rich phase are found to form for δ > 0.02. Presence of the second phase particles leads to a significant enhancement in the fracture toughness, KIC, of samples with CeO2 ≥ 0.02. The strength decreases with increasing CeO2 addition and increasing sintering time. These two factors also lead to increased PbO loss during sintering. Highest values of KIC (∼2.9 MPa m) are found in samples with δ= 0.05, sintered for 2 h.

Journal of Materials Science-materials in Electronics - J MATER SCI-MATER ELECTRON, 1999

The present study is an investigation of the structural and electrical properties of solid soluti... more The present study is an investigation of the structural and electrical properties of solid solution processed lead zirconate titanate (PZT) ceramics modified by CeO2. The PZT composition studied is Pb(Zr0.535Ti0.465)O3 modified with 0.0–0.2 mol % CeO2. Studies of the loss of lead oxide during sintering have been performed. The lead loss increases with increasing Ce in the sample up to 0.1 mol % Ce and becomes nearly constant on further addition of Ce. The lattice parameters and cell volume of the tetragonal phase of PZT also increase with addition of Ce up to 0.1 mol % Ce. The lead loss and X-ray data indicate that Ce is being reduced to Ce3+ and is going onto the A-site of the PZT perovskite system. The study concludes that controlled modification of the MPB composition of PZT using 0.1 mol % CeO2 results in substantial enhancement of piezoelectric strain coefficients, dielectric constant and electromechanical coupling coefficients.

Materials Science and Engineering: B, 2001

Mechanical, piezoelectric and dielectric properties of PZT ceramics (Pb0.98M0.02[(Zr0.535Ti0.465)... more Mechanical, piezoelectric and dielectric properties of PZT ceramics (Pb0.98M0.02[(Zr0.535Ti0.465)0.995]O3, M=Er, Gd, Eu, Nd, La and Bi) have been studied. The fraction of A sites occupied by the different additives is estimated and is found to increase with the ionic radius of the additive ion. The density is high in Bi-, Gd- and Eu-PZT samples. Small amounts of the pyrochlore phase

Materials Science and Engineering: B, 1999

The effect of net PbO content (obtained by taking into account the amount of excess PbO added and... more The effect of net PbO content (obtained by taking into account the amount of excess PbO added and PbO loss during sintering) on the mechanical and piezoelectric properties of lead zirconate titanate (PZT) ceramics has been studied. The samples were prepared by the solid state route using the morphotropic phase boundary composition Pb(Zr 0.535d Ti 0.465)O 3. Excess PbO was also added to the samples in varying amounts from 0-1.0 wt.%. To vary PbO volatility the samples were sintered with and without a PbO rich atmosphere at 1220°C for 2 h. The resulting Pb content as given by x in Pb 1 + x (Zr 0.535 Ti 0.465)O 3 + x varied from x= −1.7 ×10 − 2 to 1.8 ×10 − 2. The sintered density was found to increase with increasing lead content. The precipitation of the second phase believed to be ZrO 2 is observed for x= −1.7× 10 − 2. The fracture mode changed from intergranular to transgranular with increasing x. The fracture toughness (K IC) and strength are minimum near x =0 and increase with increasing as well as decreasing x. The maximum values of K IC and strength are 1.45 MPa m 1/2 and 90 MPa, respectively, for x =1.8× 10 − 2. The dielectric constant and piezoelectric strain coefficient d 33 increased with x.

Materials Science and Engineering: B, 1999

Single phase lead zirconate titanate (PZT) of tetragonal structure (Zr:Ti = 0.40:0.60) was modifi... more Single phase lead zirconate titanate (PZT) of tetragonal structure (Zr:Ti = 0.40:0.60) was modified using a trivalent rare earth additive Nd 2 O 3. The samples having composition Pb 1-(3x/2) Nd x (Zr 0.40 Ti 0.60)O 3 was prepared by solid state route. The Nd content in the samples was varied from 0-4 mol %. The effect of Nd 3 + additive on mechanical and electrical properties of PZT ceramics has been studied. It was observed that Nd addition results in enhancement of fracture toughness (K IC) and Vicker's hardness (H v) in the samples. Nd addition also results in substantial increase in dielectric constant and d 33 piezo coefficient of PZT ceramics. The maximum value of K IC obtained is 2.05 Mpam 1/2. Also the peak value of 680 for dielectric constant and a d 33 of 240 pCN − 1 is obtained for the same composition. Both the mechanical and electrical properties seem to peak at 2% Nd 3 + addition, which makes this composition attractive for actuator and other high power ultrasonic transducer applications. The increase in mechanical properties has been attributed the increased tetragonality (c/a ratio) and increase in sintered density with Nd addition. It seems that the ferroelastic domain switching is the main contributor to toughening in these ceramics. The increased tetragonality with Nd addition results in more work done in domain switching and, hence, enhanced toughness. The increase in electrical properties with Nd addition has been attributed to reduction in oxygen vacancies in the samples. The X-ray and the sintered density results also suggest that at 2 mol % Nd addition, Nd is reaching its solubility limit in PZT system.

International Journal of Innovation and Technology Management, 2013

Personal computers (PC) have significantly increased demand for mass market software. Computer so... more Personal computers (PC) have significantly increased demand for mass market software. Computer software has also now become an enabler for all fields of technology; innovation is inevitable for growth of this fast emerging industry. For economic viability for such innovations, there is an increased advocacy for incorporating software as a patentable subject matter forcing countries to make computer software patentable either completely or in limited form. However, patenting of computer software related inventions have not been without its own set of controversies. Not only software patents globally are being protected under vastly divergent legal perspectives, with varying interpretations of trade-related aspects of intellectual property rights (TRIPS) agreement, but are also still evolving through continued interventions from policy makers and federal courts. This has led to a very broad boundary between patentable and non-patentable subject matter and has resulted in a large numbe...

Ferroelectrics, 2001

Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the ... more Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the morphotropic phase boundary (MPB) replaced with different amounts of Ce have been prepared according to the formula Pb(Zr0.535-δTi0.465Ceδ)O3 with δ between 0.0 and 0.05. The sintering has been carried out without any atmosphere powder so as to provide a Pb deficient atmosphere and facilitate the formation of second phase particles. The loss of weight during sintering increases sharply with the initial addition of CeO2 upto δ = 0.0025. The sintered density decreases with the initial addition of CeO2 and then increases, reaching a maximum value at δ = 0.006. The x-ray and weight loss data point to Ce going to the A site in samples with low CeO2. Particles of a CeO2 rich phase are found to form for δ > 0.02. Presence of the second phase particles leads to a significant enhancement in the fracture toughness, KIC, of samples with CeO2 ≥ 0.02. The strength decreases with increasing CeO2 addition and increasing sintering time. These two factors also lead to increased PbO loss during sintering. Highest values of KIC (∼2.9 MPa m) are found in samples with δ= 0.05, sintered for 2 h.

Ferroelectrics, 2001

Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the ... more Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the morphotropic phase boundary (MPB) replaced with different amounts of Ce have been prepared according to the formula Pb(Zr0.535-δTi0.465Ceδ)O3 with δ between 0.0 and 0.05. The sintering has been carried out without any atmosphere powder so as to provide a Pb deficient atmosphere and facilitate the formation of second phase particles. The loss of weight during sintering increases sharply with the initial addition of CeO2 upto δ = 0.0025. The sintered density decreases with the initial addition of CeO2 and then increases, reaching a maximum value at δ = 0.006. The x-ray and weight loss data point to Ce going to the A site in samples with low CeO2. Particles of a CeO2 rich phase are found to form for δ > 0.02. Presence of the second phase particles leads to a significant enhancement in the fracture toughness, KIC, of samples with CeO2 ≥ 0.02. The strength decreases with increasing CeO2 ad...

Indian Journal of Public Health Research & Development

Materials Science and Engineering B Advanced Functional Solid State Materials, May 1, 1999

The effect of net PbO content (obtained by taking into account the amount of excess PbO added and... more The effect of net PbO content (obtained by taking into account the amount of excess PbO added and PbO loss during sintering) on the mechanical and piezoelectric properties of lead zirconate titanate (PZT) ceramics has been studied. The samples were prepared by the solid state route using the morphotropic phase boundary composition Pb(Zr 0.535d Ti 0.465)O 3. Excess PbO was also added to the samples in varying amounts from 0-1.0 wt.%. To vary PbO volatility the samples were sintered with and without a PbO rich atmosphere at 1220°C for 2 h. The resulting Pb content as given by x in Pb 1 + x (Zr 0.535 Ti 0.465)O 3 + x varied from x= −1.7 ×10 − 2 to 1.8 ×10 − 2. The sintered density was found to increase with increasing lead content. The precipitation of the second phase believed to be ZrO 2 is observed for x= −1.7× 10 − 2. The fracture mode changed from intergranular to transgranular with increasing x. The fracture toughness (K IC) and strength are minimum near x =0 and increase with increasing as well as decreasing x. The maximum values of K IC and strength are 1.45 MPa m 1/2 and 90 MPa, respectively, for x =1.8× 10 − 2. The dielectric constant and piezoelectric strain coefficient d 33 increased with x.

Ferroelectrics, 2001

Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the ... more Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the morphotropic phase boundary (MPB) replaced with different amounts of Ce have been prepared according to the formula Pb(Zr0.535-δTi0.465Ceδ)O3 with δ between 0.0 and 0.05. The sintering has been carried out without any atmosphere powder so as to provide a Pb deficient atmosphere and facilitate the formation of second phase particles. The loss of weight during sintering increases sharply with the initial addition of CeO2 upto δ = 0.0025. The sintered density decreases with the initial addition of CeO2 and then increases, reaching a maximum value at δ = 0.006. The x-ray and weight loss data point to Ce going to the A site in samples with low CeO2. Particles of a CeO2 rich phase are found to form for δ > 0.02. Presence of the second phase particles leads to a significant enhancement in the fracture toughness, KIC, of samples with CeO2 ≥ 0.02. The strength decreases with increasing CeO2 addition and increasing sintering time. These two factors also lead to increased PbO loss during sintering. Highest values of KIC (∼2.9 MPa m) are found in samples with δ= 0.05, sintered for 2 h.

Journal of Materials Science-materials in Electronics - J MATER SCI-MATER ELECTRON, 1999

The present study is an investigation of the structural and electrical properties of solid soluti... more The present study is an investigation of the structural and electrical properties of solid solution processed lead zirconate titanate (PZT) ceramics modified by CeO2. The PZT composition studied is Pb(Zr0.535Ti0.465)O3 modified with 0.0–0.2 mol % CeO2. Studies of the loss of lead oxide during sintering have been performed. The lead loss increases with increasing Ce in the sample up to 0.1 mol % Ce and becomes nearly constant on further addition of Ce. The lattice parameters and cell volume of the tetragonal phase of PZT also increase with addition of Ce up to 0.1 mol % Ce. The lead loss and X-ray data indicate that Ce is being reduced to Ce3+ and is going onto the A-site of the PZT perovskite system. The study concludes that controlled modification of the MPB composition of PZT using 0.1 mol % CeO2 results in substantial enhancement of piezoelectric strain coefficients, dielectric constant and electromechanical coupling coefficients.

Materials Science and Engineering: B, 2001

Mechanical, piezoelectric and dielectric properties of PZT ceramics (Pb0.98M0.02[(Zr0.535Ti0.465)... more Mechanical, piezoelectric and dielectric properties of PZT ceramics (Pb0.98M0.02[(Zr0.535Ti0.465)0.995]O3, M=Er, Gd, Eu, Nd, La and Bi) have been studied. The fraction of A sites occupied by the different additives is estimated and is found to increase with the ionic radius of the additive ion. The density is high in Bi-, Gd- and Eu-PZT samples. Small amounts of the pyrochlore phase

Materials Science and Engineering: B, 1999

The effect of net PbO content (obtained by taking into account the amount of excess PbO added and... more The effect of net PbO content (obtained by taking into account the amount of excess PbO added and PbO loss during sintering) on the mechanical and piezoelectric properties of lead zirconate titanate (PZT) ceramics has been studied. The samples were prepared by the solid state route using the morphotropic phase boundary composition Pb(Zr 0.535d Ti 0.465)O 3. Excess PbO was also added to the samples in varying amounts from 0-1.0 wt.%. To vary PbO volatility the samples were sintered with and without a PbO rich atmosphere at 1220°C for 2 h. The resulting Pb content as given by x in Pb 1 + x (Zr 0.535 Ti 0.465)O 3 + x varied from x= −1.7 ×10 − 2 to 1.8 ×10 − 2. The sintered density was found to increase with increasing lead content. The precipitation of the second phase believed to be ZrO 2 is observed for x= −1.7× 10 − 2. The fracture mode changed from intergranular to transgranular with increasing x. The fracture toughness (K IC) and strength are minimum near x =0 and increase with increasing as well as decreasing x. The maximum values of K IC and strength are 1.45 MPa m 1/2 and 90 MPa, respectively, for x =1.8× 10 − 2. The dielectric constant and piezoelectric strain coefficient d 33 increased with x.

Materials Science and Engineering: B, 1999

Single phase lead zirconate titanate (PZT) of tetragonal structure (Zr:Ti = 0.40:0.60) was modifi... more Single phase lead zirconate titanate (PZT) of tetragonal structure (Zr:Ti = 0.40:0.60) was modified using a trivalent rare earth additive Nd 2 O 3. The samples having composition Pb 1-(3x/2) Nd x (Zr 0.40 Ti 0.60)O 3 was prepared by solid state route. The Nd content in the samples was varied from 0-4 mol %. The effect of Nd 3 + additive on mechanical and electrical properties of PZT ceramics has been studied. It was observed that Nd addition results in enhancement of fracture toughness (K IC) and Vicker's hardness (H v) in the samples. Nd addition also results in substantial increase in dielectric constant and d 33 piezo coefficient of PZT ceramics. The maximum value of K IC obtained is 2.05 Mpam 1/2. Also the peak value of 680 for dielectric constant and a d 33 of 240 pCN − 1 is obtained for the same composition. Both the mechanical and electrical properties seem to peak at 2% Nd 3 + addition, which makes this composition attractive for actuator and other high power ultrasonic transducer applications. The increase in mechanical properties has been attributed the increased tetragonality (c/a ratio) and increase in sintered density with Nd addition. It seems that the ferroelastic domain switching is the main contributor to toughening in these ceramics. The increased tetragonality with Nd addition results in more work done in domain switching and, hence, enhanced toughness. The increase in electrical properties with Nd addition has been attributed to reduction in oxygen vacancies in the samples. The X-ray and the sintered density results also suggest that at 2 mol % Nd addition, Nd is reaching its solubility limit in PZT system.

International Journal of Innovation and Technology Management, 2013

Personal computers (PC) have significantly increased demand for mass market software. Computer so... more Personal computers (PC) have significantly increased demand for mass market software. Computer software has also now become an enabler for all fields of technology; innovation is inevitable for growth of this fast emerging industry. For economic viability for such innovations, there is an increased advocacy for incorporating software as a patentable subject matter forcing countries to make computer software patentable either completely or in limited form. However, patenting of computer software related inventions have not been without its own set of controversies. Not only software patents globally are being protected under vastly divergent legal perspectives, with varying interpretations of trade-related aspects of intellectual property rights (TRIPS) agreement, but are also still evolving through continued interventions from policy makers and federal courts. This has led to a very broad boundary between patentable and non-patentable subject matter and has resulted in a large numbe...

Ferroelectrics, 2001

Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the ... more Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the morphotropic phase boundary (MPB) replaced with different amounts of Ce have been prepared according to the formula Pb(Zr0.535-δTi0.465Ceδ)O3 with δ between 0.0 and 0.05. The sintering has been carried out without any atmosphere powder so as to provide a Pb deficient atmosphere and facilitate the formation of second phase particles. The loss of weight during sintering increases sharply with the initial addition of CeO2 upto δ = 0.0025. The sintered density decreases with the initial addition of CeO2 and then increases, reaching a maximum value at δ = 0.006. The x-ray and weight loss data point to Ce going to the A site in samples with low CeO2. Particles of a CeO2 rich phase are found to form for δ > 0.02. Presence of the second phase particles leads to a significant enhancement in the fracture toughness, KIC, of samples with CeO2 ≥ 0.02. The strength decreases with increasing CeO2 addition and increasing sintering time. These two factors also lead to increased PbO loss during sintering. Highest values of KIC (∼2.9 MPa m) are found in samples with δ= 0.05, sintered for 2 h.

Ferroelectrics, 2001

Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the ... more Samples of lead zirconate titanate (PZT) with part of Zr in the composition corresponding to the morphotropic phase boundary (MPB) replaced with different amounts of Ce have been prepared according to the formula Pb(Zr0.535-δTi0.465Ceδ)O3 with δ between 0.0 and 0.05. The sintering has been carried out without any atmosphere powder so as to provide a Pb deficient atmosphere and facilitate the formation of second phase particles. The loss of weight during sintering increases sharply with the initial addition of CeO2 upto δ = 0.0025. The sintered density decreases with the initial addition of CeO2 and then increases, reaching a maximum value at δ = 0.006. The x-ray and weight loss data point to Ce going to the A site in samples with low CeO2. Particles of a CeO2 rich phase are found to form for δ > 0.02. Presence of the second phase particles leads to a significant enhancement in the fracture toughness, KIC, of samples with CeO2 ≥ 0.02. The strength decreases with increasing CeO2 ad...