Halil Güler

The synthesis of sodium sulfide pentahydrate, Na2S·5H2O, through a solid-gas reaction of sulfidizing gas mixture with sodium carbonate, Na2CO3

In this study, the sulfidization of Na2CO3 was investigated by using a solid-gas reaction under a sulfidizing gas mixture, which consisted of COS, CS2, and S2 gases. Sodium sulfide pentahydrate, Na2S·5H2O, was prepared from sodium carbonate, Na2CO3, via a sulfidizing gas mixture by a solid-gas reaction under the cooling of a nitrogen atmosphere. The observed phase was found to be the pentahydrated form of sodium sulfide. This crystalline form was determined by X-ray powder diffraction (XRD) technique. Since sodium sulfide is strongly hygroscopic, the pentahydrated crystalline form was observed in XRD measurements for all repeated experiments. The crystal unit cell parameters of the synthesized product were in excellent agreement with values given in the JCPDS card number 18-1249. The sodium sulfide pentahydrate has an orthorhombic crystal structure with the unit cell parameters of a = 6.475, b = 12.55, C = 8.655 Å, space group, Cmcm and Z = 4.

Synthesis of Sodium Neodymium Diphosphate, NaNdP2O7, and Its Powder XRD Data and IR Spectra

NaNdP2O7 was synthesized by the solution reaction of NdCl3 with Na4P2O7 and heated the precipitate at 650°C for 6–7 h. The X-ray powder diffraction data of this compound was indexed in the orthorhombic system with the refined unit-cell parameters of a = 12.579(7), b = 15.10(1), and c = 16.03(1)Å, which were in good agreement with the reported data of NaGdP2O7. It was found that NaLnP2O7 compounds (Ln: La, Eu, Gd, and Y) cannot be synthesized by this method, but NaCeP2O7 has been prepared as an amorphous product. The IR spectra of NaNdP2O7 also agreed with the IR data of NaGdP2O7 with the presence of P2O7 4− vibrational modes.

Synthesis and Characterizations of LaM2M'3S6-y (M: Mg, Ca, Sr, Ba ; M':Cu, Fe), La2SrS4 and La2CaS4

YM2M’3S6-y , (M= Ca, Sr, Ba, Mg and M′= Cu, Fe) type of compounds were synthesized and the effect of rare earth elements on these type of compounds was investigated. By replacing Y with La, LaBa2Cu3S6-y compound was synthesized based on solid-gas reaction and the obtained samples were characterized by XRD, IR and EDX methods. Crystal structure of LaBa2Cu3S6-y was orthorhombic and refined unit cell parameters were a =10.16(1), b=12.72(2) and c=13.54(0)Å. This compound showed a semiconducting behavior in the range 78-300 °K. After the replacement of La element with Gd and Dy, as result of the sulfidizing process for both rare earths, GdO2S and DyO2S compounds were observed in the X-ray pattern of the products. When Ba is replaced with Sr and Ca, the La2SrS4 and La2CaS4 products were obtained. These two compounds were synthesized first time by solid-gas sulfidizing reaction method. The La2CaS4 ceramic has become a novel optical window material lately for 8-14 μm IR range.

Solid-State Synthesis of Pb2Sr2CaCu3-ySx and Conducting Properties

In this study complete substitution of O by S in Pb-Sr-Ca-Cu-O superconducting system that has the general formula Pb2Sr2MCu3O8+δ (M = Y, Ca) had been attempted. For this purpose, solid-gas reactions of solid mixture, PbO, Sr(NO3)2, CaO and CuO with a sulfidizing gas consisted of COS, CS2, CO, CO2 and sulfur vapour were performed. For M, only Ca was used. The obtained product Pb2Sr2CaCu3-ySx, was characterized by XRD, IR, SEM, EDX, conductivity measurements and chemical analysis. X-Ray powder diffraction pattern of Pb2Sr2CaCu3-ySx was found to be very similar to PbS diffraction pattern reported in JCPDS Card No.5-592 which has a rocksalt structure with a = 5.946 Å. Pb2Sr2CaCu3-ySx was indexed in monoclinic system with the refined unit cell parameters of a = 5.947(8), b=5.941(3), c=11.98(1) Å and β=90.19(9). Since ‘c’ unit cell dimension is almost twice of a and b, it is concluded that a superstructure formation had resulted which is common for complex sulfides. The absence of metal oxygen bands in IR and O bands in EDX spectra is taken to be the proof of the complete substitution of O by S by solid gas reactions. The conductivity of Pb2Sr2CaCu3-ySx was measured by four-probe conductivity technique and was found to be metallic.

Hydrothermal synthesis and structural investigation of a new polymorph form of NdBO3

The present work deals with the hydrothermal synthesis of a new polymorph form of neodymium orthoborate, NdBO3. It was obtained by dissolving 0.1875g B2O3 in 20 ml distilled water and later added to 1.8125 g Nd2O3 and the mixture was transferred to a teflon autoclave. The hydrothermal reaction was performed at 230 °C for 72 h. Characterizations of the sample were carried out by using X-Ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermal Analysis (DTA/TG) techniques. NdBO3 was crystallized in monoclinic system and unit cell parameters were calculated as a=11.726(1) A, b= 6.759(2) A, c= 9.909(4) A, β= 114.50(0)°, and space group of C2/c. It was confirmed that NdBO3 was isostructural with the form of Er doped YBO3 (a=11.3138(3) A, b=6.5403(2) A, c= 9.5499(2) A and β= 112.902(1)°) at room temperature. The other significant invention of NdBO3 was thermally stable up to 700 °C, but if the specimen was heated at 780 °C for 4 h, the monoclinic crystal structure was transformed...