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Papers by Elizabeth Chavira

Bulletin of the American Physical Society, 2018

Iranian Journal of Materials Science and Engineering, 2019

The superconducting properties of the RuSr 2 GdCu 2 O 8 ceramic system depend strongly on the syn... more The superconducting properties of the RuSr 2 GdCu 2 O 8 ceramic system depend strongly on the synthesis conditions and the ionic substitutions. In this work, we studied the structural and electrical properties of the Ru 0.9 M 0.1 Sr 2 GdCu 2 O 8 system, with M = Zr, Mo, and Mn. The samples were prepared by solid-state reaction at ambient pressure in air, using temperatures between 980 °C and 1020 °C. X-ray powder diffraction patterns indicated that all samples crystallized in a tetragonal symmetry (S.G. P4/mmm, No. 123). The structural data of each sample was re ned by the Rietveld method, showing that the Cu-O (1) and Ru-O (1) bond lengths varies with the substituted ionic radii of Zr, Mo, and Mn ions. Electrical resistance measurements indicated that the samples annealed in owing oxygen at 1050 °C and 1055 °C for 5 days exhibit a semiconductor like behavior for M = Mo and Mn, whereas the samples with M = Zr and Ru show superconductivity behavior.

Journal of Materials Science and Engineering B, Aug 28, 2018

Studies of thermodynamic, electric and magnetic properties were conducted on the (K x Sr 1-x)CrO ... more Studies of thermodynamic, electric and magnetic properties were conducted on the (K x Sr 1-x)CrO z , x = 0.10, 0.15 and 0.50 system; adjusted for different crystal sizes (polycrystalline, nano-crystalline and single crystals). For polycrystals, a solid-state reaction method was used (room temperature, T R , up to 665 °C). Nano-crystals, a crushing technique with a mechanical mortar were processed at T R. Single crystals were acquired, through fusion method starting from polycrystals pre-manufactured (665 °C) over 900 °C. For the methods described above, they all were worked at atmospheric pressure. Studying the thermodynamic in the crystals mixture were obtained by TGA (thermogravimetric analysis) and DSC (differential scanning calorimetry). Powder XRD (X-ray diffraction) in the manual grinding mixture a SrCO 3 solid solution, at T R was detected. When increasing the temperature, a solid solution of K 2 Sr(CrO 4) 2 is formed. By HRTEM (high-resolution transmission electronic microscope), crystal sizes 4-12 nm were seen. (K 0.50 Sr 0.50)CrO z composition presents a weak ferromagnetic and an insulating behavior.

Physical Review B

ABSTRACT

Journal of the Mexican Chemical Society, Oct 12, 2017

Thermal analyses, X-ray diffraction (XRD), and HR-XRD (High Resolution XRD) were used to identify... more Thermal analyses, X-ray diffraction (XRD), and HR-XRD (High Resolution XRD) were used to identify thermal behavior products in a family of solid-state reactions involving rare earth (REE) reagents. REE where sorted in light and heavy groups. The general reactions under study were: REE 2 O 3 + Fe 2 O 3 + As 2 O 3 → 2REEFeO 3 + As 2 O 3 ↑ and 2REE(OH) 3 + Fe 2 O 3 + As 2 O 3 → 2REEFeO 3 + As 2 O 3 ↑ + 3H 2 O↑, REE= La, Ce, Nd, Sm, Gd, Dy, Ho, Er, and Yb. Based on the experimental results, it is possible to predict the different compounds of REE products in a series of reactions analyzing only three of the reactions, two for light REE and one for heavy REE.

An improved acrylamide sol-gel technique using a microwave oven in order to synthesize bimetallic... more An improved acrylamide sol-gel technique using a microwave oven in order to synthesize bimetallic Rh-Pd particles is reported and discussed. The synthesis of Pd and Rh nanoparticles was carried out separately. The polymerization to form the gel of both Rh and Pd was carried out at 80 ∘ C under constant agitations. The method chosen to prepare the Rh and Pd xerogels involved the decomposition of both gels. The process begins by steadily increasing the temperature of the gel inside a microwave oven (from 80 ∘ C to 170 ∘ C). In order to eliminate the by-products generated during the sol-gel reaction, a heat treatment at a temperature of 1000 ∘ C for 2 h in inert atmosphere was carried out. After the heat treatment, the particle size increased from 50 nm to 200 nm, producing the bimetallic Rh-Pd clusters. It can be concluded that the reported microwave-assisted, sol-gel method was able to obtain nano-bimetallic Rh-Pd particles with an average size of 75 nm.

International Journal of …, 2010

... Structural and electronic properties of cubic CeO 2 : Unpaired electrons in CeO 2. Carlos Qui... more ... Structural and electronic properties of cubic CeO 2 : Unpaired electrons in CeO 2. Carlos Quintanar 1,* ,; Reyna Caballero 1 ,; Jorge Barreto 2 ,; Elizabeth Chavira 3 ,; Ernesto E. Marinero 4. ... 17 Dunlap, BI; Connolly, JWD; Sabin, JR J Chem Phys 1979, 71, 4993. ...

Acta Crystallographica Section E Structure Reports Online, 2009

inorganic compounds i50 Rosales et al. Y 0.76 Ho 0.24 FeGe 2 O 7 Acta Cryst. (2009). E65, i49-i50... more inorganic compounds i50 Rosales et al. Y 0.76 Ho 0.24 FeGe 2 O 7 Acta Cryst. (2009). E65, i49-i50 supplementary materials supplementary materials sup-1

Ceramics International, 2012

Pure superconducting phases with some of the highest transition temperatures for their phases are... more Pure superconducting phases with some of the highest transition temperatures for their phases are reported.

International Journal of Quantum Chemistry, 2010