scholarly journals X-ray diffraction and Raman spectroscopic studies of Zn-substituted carrboydite-like compounds

2006 ◽  
Vol 100 (1) ◽  
pp. 174-186 ◽  
Author(s):  
Yu-Hsiang Lin ◽  
Moses O. Adebajo ◽  
J. Theo Kloprogge ◽  
Wayde N. Martens ◽  
Ray L. Frost
2001 ◽  
Vol 16 (4) ◽  
pp. 903-906 ◽  
Author(s):  
M. S. Tomar ◽  
R. Melgarejo ◽  
P. S. Dobal ◽  
R. S. Katiyar

Zn1–xMgxO is an important material for optoelectronic devices. We synthesized this material using a solution-based route. We investigated in detail the structural behavior of this material system using x-ray diffraction and Raman spectroscopy. Mg substitution up to x ≈ 0.10 does not change the crystal structure, as revealed by x-ray diffraction and Raman spectroscopic studies. This synthesis route is also suitable to prepare thin films by spin coating with the possibility of p and n doping.


2004 ◽  
Vol 68 (3) ◽  
pp. 433-441 ◽  
Author(s):  
A. K. Kleppe ◽  
A. P. Jephcoat

AbstractWe report micro-Raman spectroscopic studies of FeS2 pyrite in the diamond-anvil cell under hydrostatic and non-hydrostatic conditions to 55 GPa at room temperature. Four out of five Ramanactive modes are resolved with helium as a pressure-transmitting medium to highest pressures. The fifth mode, Tg(2) [377 cm-1], is weak and unresolved lying ∼2 cm-1 from the intense Ag mode [379 cm-1] at 1 bar. We observe an increase in the separation of the Eg [344 cm-1] and Tg(1) [350 cm-1] modes under compression. All observed frequencies increase continuously with increasing pressure showing no evidence for a structural phase transition in accord with both X-ray diffraction and shock-wave studies. The Ag and Tg(1) modes gain significantly in intensity relative to the Eg mode with increasing pressure probably resulting from Raman resonance effects. The Tg(3) mode [430 cm-1] broadens unusually compared to the other pyrite modes with pressure. The Raman data are consistent with a contraction of the S-S and Fe-S bonds under pressure. The main effect of non-hydrostatic conditions on the Raman modes is a strong pressure-induced broadening; the pressure-dependence of the frequencies and relative intensities are not affected within the error of the measurements.


1991 ◽  
Vol 95 (24) ◽  
pp. 10098-10103 ◽  
Author(s):  
Toshiyuki Takamuku ◽  
Toshio Yamaguchi ◽  
Hisanobu Wakita

2003 ◽  
Vol 68 (9) ◽  
Author(s):  
Zhongwu Wang ◽  
R. T. Downs ◽  
V. Pischedda ◽  
R. Shetty ◽  
S. K. Saxena ◽  
...  

2017 ◽  
Vol 32 (S1) ◽  
pp. S40-S51
Author(s):  
Abderrahim Aatiq ◽  
Asmaa Marchoud ◽  
Hajar Bellefqih ◽  
My Rachid Tigha

Structures of the two M0.50SbFe(PO4)3 (M = Mg, Ni) phases, abbreviated as [Mg0.50] and [Ni0.50], were determined at room temperature from X-ray diffraction (XRD) powder data using the Rietveld analysis. Both compounds belong to the NASICON structural family. XRD patterns of [Mg0.50] and [Ni0.50] phases were easily indexed with a primitive hexagonal unit cell [P$\overline 3 $ space group, Z = 6] similar to that already obtained for La0.33Zr2(PO4)3. Obtained unit cells parameters are [a = 8.3443(1) Å, c = 22.3629(1) Å], and [a = 8.3384(1), c = 22.3456(1) Å], respectively, for [Mg0.50] and [Ni0.50] phosphates. In both samples, the [Sb(Fe)(PO4)3]− NASICON framework is preserved and a partially-ordered distribution of Sb5+ and Fe3+ ions is observed. Raman spectroscopic study was used to obtain further structural information about the nature of bonding in [Mg0.50] and [Ni0.50] phases.


2010 ◽  
Vol 12 (3,4) ◽  
pp. 207
Author(s):  
H. Bih ◽  
L. Bih ◽  
M.P.F. Graça ◽  
M.A. Valente ◽  
B. Elouadi

<p>Phosphate glasses in the system (50-x)A<sub>2</sub>O-xMoO<sub>3</sub>-10Nb<sub>2</sub>O<sub>5</sub>-40P<sub>2</sub>O<sub>5</sub> (AMo-40), with x=0; 30 and A=Li or Na were prepared by the melt quenching method. The effect in the crystallization behaviour of the glass due to the introduction of MoO<sub>3</sub> in the glass composition and varying the molar ratio between network modifiers and network formers (M/F) was studied. The prepared glasses were heat-treated in air, at 550, 600 and 650 ºC for 4 hours. The structure, of the obtained samples, was studied by differential thermal analysis (DTA), X-ray powder diffraction (XRD), Raman spectroscopy and the morphology by scanning electron microscopy (SEM). It was found that the replacement of Li<sub>2</sub>O or Na<sub>2</sub>O by MoO<sub>3</sub> reduces the number of the crystallised phases. In the lithium-niobiophosphate glasses the presence of MoO<sub>3</sub> promotes the formation of NbOPO<sub>4</sub> and reduces the formation of ortho- and pyro-phosphate phases. The thermal treatments affect the arrangements of the network structure of the AMo-40-glasses.</p>


2014 ◽  
Vol 34 (3) ◽  
pp. 289-296 ◽  
Author(s):  
Hisako Hirai ◽  
Hirokazu Kadobayashi ◽  
Takahiro Matsuoka ◽  
Yasuo Ohishi ◽  
Yoshitaka Yamamoto

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 490
Author(s):  
Varsha Singh ◽  
Anil Kumar Paidi ◽  
Cheol-Hwee Shim ◽  
So Hee Kim ◽  
Sung Ok Won ◽  
...  

For the present work, calcite nanocrystals were grown by annealing precursors at 500 °C. These precursors were obtained by three different thermal schemes. Among these schemes, two involve heating at 100 °C for 16 h and 16 + 24 h, respectively. In the third scheme, heating was performed at 100 °C for 16 h, followed by annealing at 300 °C for 24 h. X-ray diffraction studies, followed by Fourier transform infrared and Raman spectroscopic studies, exhibited the formation of calcite phase of calcium carbonate. Transmission electron microscopy showed that particle sizes of synthesized calcite nanocrystals were in the range of 25–40 nm. Onsets of shape change were also observed with different thermal schemes, using these measurements. X-ray absorption spectroscopy envisaged that the coordination numbers of Ca-O and Ca-Ca shell were not influenced by the thermal schemes; however, bond lengths of these shells were modified. This study in the near edge region evidenced the manifestation of a local electronic structure of calcite when kept in an open environment, depending upon different thermal schemes.


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