Kwon, Young-Uk,Corbett, John D.

, p. 219 - 228 (1992)

Synthesis, crystal structure, and properties of HfM′P (M′ = Fe, Co, Ni) in comparison to ZrNiP

Kleinke,Franzen

, p. 1893 - 1900 (1996)

The new phosphides HfM′P (M′ = Fe, Co, Ni) have been synthesized by arc melting of HfP and the corresponding 3 d metal, and subsequent annealing at 1400°C. The lattice constants vary from a = 6.247(2) A, b = 3.7177(6) A, c = 7.137(2) A, V = 165.74(8) A3 for HfFeP, a = 6.295(3) A, b = 3.668(2) A, c = 7.175(4) A, V = 165.7(2) A3 for HfCoP to a = 6.240(3) A, b = 3.716(2) A, c = 7.135(2) A, V = 165.4(2) A3 (HfNiP) in the orthorhombic space group Pnma. Although ZrNiP occurs only in the Ni2In structure type, all three Hf phosphides crystallize in the Co2Si structure type, isotypic to ZrFeP and ZrCoP. The structural differences between HfNiP and ZrNiP can be explained by the preference of Hf for structures with more metal-metal bonds rather than by size effects. Johann Ambrosius Barth 1996.

Self-propagating metathesis routes to metastable group 4 phosphides

Jarvis Jr., Robert F.,Jacubinas, Richard M.,Kaner, Richard B.

, p. 3243 - 3246 (2000)

Group 4 phosphides, which are typically prepared at high temperatures (>800 °C) over several days, are synthesized in self-propagating metathesis (exchange) reactions in seconds. These reactions produce cubic forms of zirconium phosphide (ZrP) and hafnium phosphide (HfP) which are normally made at temperatures greater than 1425 °C and 1600 °C, respectively. To test whether the high temperatures reached in the metathesis reactions are responsible for the formation of the cubic phases, inert salts are added to lower the maximum reaction temperatures. The lower temperature reactions still result in cubic phosphides, although smaller crystallites form. Further experiments with phosphorus addition indicate that the phosphorus content is not responsible for cubic phase formation. Templating is ruled out using lattice mismatched KCl and hexagonal ZnS as additives. Therefore, the direct synthesis of the high-temperature cubic phase in metathesis reactions appears to be caused by nucleation of the metastable cubic form that is then trapped by rapid cooling. Heating the cubic phase of either ZrP or HfP to 1000 °C for 18 h, or carrying out metathesis reactions in sealed ampules at 1000 °C, results only in the hexagonal phase.

The crystal structure of HfZrP

Zeng, Lingmin,Franzen, Hugo F.

, p. 119 - 122 (1998)

The crystal structure of HfZrP has been determined using single crystal X-ray diffraction data. This compound crystallizes in the orthorhombic space group Cmmm (No.65), with a=19.004(3), b=29.372(4), c=3.565(1) A and the Zr2P structure type. The Hf and Zr atoms are disordered on one site with total occupancy of 1.0. X-ray powder patterns indicate that (HfxZr1-x)2P alloys consist of single phase (Zr2P-type),two phases and single phase (Hf2P-type) corresponding to 0≤.x≤0.5, 0.5≤.x≤0.8 and 0.8≤.x≤1.0, respectively.

Selective production of γ-Valerolactone from ethyl levulinate by catalytic transfer hydrogenation over Zr-based catalyst

Zhang, Zhongze,Liu, Zonghui,Gu, Zhiyuan,Wen, Zhe,Xue, Bing

, p. 1181 - 1198 (2022/02/05)

The catalytic transfer hydrogenation (CTH) reaction of ethyl levulinate (EL) with alcohol to γ-valerolactone (GVL) has been investigated over a series of Zr-based catalysts, including ZrO2, ZrP, Zrβ, ZrP/Hβ and ZrO2/HZSM-5. It is found that the simplest ZrO2 was the most efficient for GVL production, giving an EL conversion as high as 97% and GVL selectivity of 91% after 7?h at 170?°C using 2-propanol as the hydrogen donor and solvent. The effects of reaction temperature, time and solvent on catalytic performance were investigated. Moreover, the kinetic behavior of CTH reaction of EL was also studied over ZrO2 catalyst. The as-prepared ZrO2 gives an Ea value of 32.9?kJ/mol, which is much lower than other catalysts in the literatures. Furthermore, those catalysts have been, respectively, characterized by XRD, IR, BET and NH3-TPD techniques to reveal the physical properties and structures of these materials. Correlating the catalyst performance with its physical and chemical properties uncovers that the higher pore diameter, lower total acidity and higher Lewis acid sites of catalyst surface would be the key to the catalyst performance. Graphical abstract: [Figure not available: see fulltext.]