Phase Transformation of Nanocrystalline CdS Synthesized by Solvothermal Reaction

2007 ◽  
Vol 544-545 ◽  
pp. 777-780
Author(s):  
Titipun Thongtem ◽  
Anukorn Phuruangrat ◽  
Somchai Thongtem
Keyword(s):  
Phase Transformation ◽  
Pure Water ◽  
Longitudinal Optical ◽  
Ammonia Solution ◽  
Solvothermal Reaction ◽  
Raman Analysis ◽  
Pl Spectra

CdS was synthesized by solvothermal reaction of CdCl2.2.5H2O and (NH2)2CS in ammonia solution at 200 oC for 10 h. XRD, TEM and SAED show that the products are nanocrystalline CdS. The phase is 100 % hexagonal (hcp) in pure water, gradually transformed into cubic with the increase of NH3 concentration, and 100 % cubic in 25 % NH3 solution. By using FTIR, no solvents were detected in the products. Raman analysis revealed the presence of 1LO (longitudinal optical) and 2LO phonon peaks at 297.0 and 597.1 cm-1 for CdS (hcp), and 295.9 and 596.9 cm-1 for CdS (cubic), respectively. Strong peaks of the photoluminescent (PL) spectra were detected at 450 nm for hcp, and 519 nm for cubic.

Solvothermal Preparation of Nano-Sized CaWO4 Particles

2007 ◽  
Vol 124-126 ◽  
pp. 1265-1268 ◽  
Author(s):  
Sulawan Kaowphong ◽  
Titipun Thongtem ◽  
Somchai Thongtem
Keyword(s):  
Pure Water ◽  
Solvothermal Reaction ◽  
Hrtem Image ◽  
Scheelite Structure ◽  
Glycerol Water ◽  
Calcium Salts ◽  
Solvothermal Preparation

CaWO4 was prepared by solvothermal reaction of Na2WO4.2H2O and calcium salts (CaCl2.2H2O, Ca(NO3)2.4H2O and Ca(CH3COO)2) in solvent containing a variety of glycerol/water ratios at 160 oC for 6 h. By using XRD, SEM, TEM and ED, the products compose of nano-sized CaWO4 particles with scheelite structure but different morphologies. Interplanar spaces between (101) planes were determined from HRTEM image, ED patterns and XRD spectra are 0.424, 0.474 and 0.476 nm, respectively. Luminescent intensities of the products prepared in pure water are the highest and their central peaks are the same at 444 nm. In addition, Ca, W and O were detected using EDX.

scholarly journals Quantitatively Analyzing Pressure Induced Phase Transformation by Photoluminescence Spectra in Eu3+-doped Sodium Potassium Bismuth Titanate

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 881
Author(s):  
Liang Zeng ◽  
Ji Zhou
Keyword(s):  
Phase Transformation ◽  
Trigger Point ◽  
Rhombohedral Phase ◽  
Fluorescence Intensity Ratio ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Sodium Potassium ◽  
Pl Spectra ◽  
Quantitative Analyses ◽  
T Phase

(Na0.8,K0.2)0.5Bi0.497Eu0.003TiO3 (NKBET20) piezoelectric ceramic powders were prepared by the solid-reaction method. The phase structures of the NKBET20 powders under various pressures were investigated by photoluminescence (PL) spectra and X-ray diffraction (XRD). The PL spectra of the doped Eu3+ ions suggest a pressure induced transformation from the tetragonal to rhombohedral phase (R phase), and the phase transformations were confirmed by XRD analyses. Furthermore, the fluorescence intensity ratio of the D 0 5 → F 2 7 transition to the D 0 5 → F 1 7 transition (FIR21) could be utilized for the quantitative analyses of the phase transformation. The results from the PL method show that as the pressure increases from 0 to 500 MPa, the fractions of the R phase of the NKBET20 powders increase from about 11% to 58%, while the fractions of the tetragonal phase (T phase) decrease from about 89% to 42%, which are consistent with the XRD Rietveld refinement. Unlike the ceramic bulks, the pressure induced phase transformation in the ceramic powders shows no obvious trigger point and is much gentler. This work suggests a different viewpoint to study the pressure induced phase transformation qualitatively and quantitatively, which can be used for more phase analyses.

Characterization of Nano-Rod ZnWO4 Prepared by Surfactant-Assisting Solvothermal Reaction

2007 ◽  
Vol 544-545 ◽  
pp. 685-688 ◽  
Author(s):  
Titipun Thongtem ◽  
Suttasinee Katunyoo ◽  
Somchai Thongtem
Keyword(s):  
Solvothermal Reaction ◽  
Pyridinium Chloride ◽  
Cetyl Pyridinium Chloride ◽  
Pl Spectra ◽  
Ph Values ◽  
Nano Rods ◽  
Stretching Vibrations ◽  
Cetyl Pyridinium

Nano-rod ZnWO4 was solvothermally prepared by the reaction of Zn(CH3COO)2.2H2O with Na2(WO4).2H2O in water at 150-200 oC using the pH of 5.0, 7.0, 9.0 and 12.0 for 24, 48 and 72 h. N-cetyl pyridinium chloride was used as a surfactant. By using XRD, SAED, EDX and TEM, nano-rod ZnWO4 containing Zn, W and O was detected. The pH values can play a role in the length of the nano-rods and their crystallinities. FTIR revealed the presence of Zn-O-W, W-O and Zn-O stretching vibrations of the products. Their photoluminescent (PL) spectra are similar and the wavelengths at the highest intensities were detected over the range of 445-450 nm.

Porosity-Induced Optical Phonon Engineering in III-V Compounds

1998 ◽  
Vol 536 ◽  
Author(s):  
I. M. Tiginyanu ◽  
G. Irmer ◽  
J. Monecke ◽  
H. L. Hartnagel ◽  
A. Vogt ◽  
...  
Keyword(s):  
Optical Phonon ◽  
Phonon Frequency ◽  
Vibrational Mode ◽  
Longitudinal Optical ◽  
Electrochemical Anodization ◽  
Raman Analysis ◽  
Porous Layers ◽  
Surface Phonon ◽  
Promising Tool ◽  
Phonon Spectra

AbstractNew possibilities for modifying the phonon spectra of III-V compounds are evidenced by micro-Raman analysis of porous layers prepared by electrochemical anodization of (111 )Aoriented n-GaP substrates. In particular, a surface-related vibrational mode along with a porosity-induced decoupling between the longitudinal optical (LO) phonon and plasmon are observed. We prove that filling in the pores with other materials (aniline as a first approach) is a promising tool for controlling the surface phonon frequency.

Raman analysis of the E1 and A1 quasi-longitudinal optical and quasi-transverse optical modes in wurtzite AlN

1999 ◽  
Vol 85 (7) ◽  
pp. 3535-3539 ◽  
Author(s):  
Leah Bergman ◽  
Mitra Dutta ◽  
Cengiz Balkas ◽  
Robert F. Davis ◽  
James A. Christman ◽  
...  
Keyword(s):  
Longitudinal Optical ◽  
Transverse Optical ◽  
Raman Analysis ◽  
Optical Modes

Raman analysis of longitudinal optical phonon-plasmon coupled modes of aligned ZnO nanorods

2009 ◽  
Vol 105 (7) ◽  
pp. 073104 ◽  
Author(s):  
An-Jen Cheng ◽  
Yonhua Tzeng ◽  
Hui Xu ◽  
Siddharth Alur ◽  
Yaqi Wang ◽  
...  
Keyword(s):  
Optical Phonon ◽  
Zno Nanorods ◽  
Longitudinal Optical ◽  
Longitudinal Optical Phonon ◽  
Coupled Modes ◽  
Raman Analysis

Raman Analysis of the Silicon Wafer Scratched by Single Point Diamond

2011 ◽  
Vol 175 ◽  
pp. 82-86
Author(s):  
Zhuo Chen ◽  
Xin Wei ◽  
Xiao Zhu Xie ◽  
Qing Lei Ren
Keyword(s):  
Mathematical Model ◽  
Phase Transformation ◽  
Silicon Wafer ◽  
Silicon Surface ◽  
Applied Load ◽  
Single Point ◽  
Monocrystalline Silicon ◽  
Raman Analysis ◽  
Silicon Based ◽  
The Relationship

This paper presents a Raman analysis of the monocrystalline silicon wafer scratched by single point diamond. Si-III and Si-XII phases are found to be existence in the scratched silicon surface, which is the result of the phase transformation. A mathematical model was developed to calculating the molar concentration of phase of the silicon. Based on the mathemathical model, the relationship between the molar concentrations of the Si-I phase and the applied load was analysied.

Effects of Temperature and Mineralizer on In2O3 Crystals Synthesized by Hydrothermal Method

2014 ◽  
Vol 884-885 ◽  
pp. 287-291
Author(s):  
Wen Li Zheng ◽  
Wei Yang
Keyword(s):  
Phase Transformation ◽  
Hydrothermal Method ◽  
Crystalline Phase ◽  
Fill Factor ◽  
Pure Water ◽  
Transformation Rule ◽  
Secondary Crystallization ◽  
Different Temperatures ◽  
Effects Of Temperature

In ( OH )3, InOOH and In2O3crystals were synthesized by hydrothermal method, using pure water, 1mol/L KOH and 5mol/L KOH as mineralizer, the fill factor of 35%, reacted at the temperature of 200°C, 250°C and 350°C respectively, and time of 24 h. The phase transformation rule of In ( OH )3, InOOH and In2O3was studied in different temperatures and mineralizer, and their morphology have been analyzed. When pure water was used, temperature was 200°C , the results showed that In ( OH )3crystalline phase was no obvious transformation and secondary crystallization, the crystal had nonspecific morphology. While temperature was 250°C and 350°C, the In ( OH )3crystal transformed into InOOH. When 1 mol/L KOH and 5 mol/L KOH was used, temperature was 200°C , the In ( OH )3crystal had secondary crystallization. In particular, the largest-scale crystal was about 20 μm, the smallest crystal was less than 200 nm when 5 mol/L KOH was used. InOOH crystal and a small amount of In2O3were obtained in 250°C. When temperature reached 350°C , the In2O3with cubic bixbyite structure was obtained, exposing the faces { 001}, { 010}, { 100} and { 101}, and the length of crystal side was more than 50 μm.

Micro-Raman Study of Charge Carrier Distribution and Cathodoluminescence Microanalysis of Porous gap Membranes

1999 ◽  
Vol 588 ◽  
Author(s):  
I. M. Tiginyanu ◽  
M. A. Stevens Kalceff ◽  
A. Sarua ◽  
G. Irmer ◽  
J. Monecke ◽  
...  
Keyword(s):  
Longitudinal Optical ◽  
Sulphuric Acid Solution ◽  
Porous Membranes ◽  
Specific Information ◽  
Carrier Distribution ◽  
Free Standing ◽  
Raman Analysis ◽  
Porous Layers ◽  
Emission Efficiency ◽  
Raman Study

AbstractPorous layers and free-standing membranes were fabricated by anodic etching of n-GaP substrates in a sulphuric acid solution. Micro-Raman analysis of the interaction between the longitudinal optical phonons and plasmons in porous membranes allowed us to obtain specific information about the electro-optical properties of microstructured GaP. In particular, apart from the carrier exhausted areas surrounding the pores, the existence of conductive regions was demonstrated. A comparative analysis of the secondary electron and panchromatic cathodoluminescence (CL) images evidenced an increase in the emission efficiency caused by porosity. Data concerning the spectral distribution of CL in bulk and porous samples are presented.

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