Observation of the Ammonium Salt of 12-Molybdophosphoric Acid by in Situ Raman Spectroscopy during Solid-State Synthesis: Spectral Analysis and Reconstruction Using the Band-Target Entropy Minimizatio

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• 作者：Chilukoti Srilakshmi* ; Wee Chew ; Kanaparthi Ramesh ; Marc Garland*
• 刊名：Inorganic Chemistry
• 出版年：2009
• 出版时间：March 2, 2009
• 年：2009
• 卷：48
• 期：5
• 页码：1967-1973
• 全文大小：187K
• 年卷期：v.48,no.5(March 2, 2009)
• ISSN：1520-510X

文摘

The solid-state reaction between ammonium heptamolybdate (AHM) and zirconium phosphate (ZrP) to give the ammonium salt of 12-molybdophosphoric acid (AMPA) was performed at 25−400 °C and monitored using in situ Raman spectroscopy. Spectral analysis of the Raman data using the band-target entropy minimization (BTEM) algorithm resulted in spectral estimates for the starting materials and product, AHM, ZrP, and AMPA, as well as the byproduct MoO₃ and an intermediate 11(NH₄)₂O·4(MoO₃)₇. The time-dependent relative concentration profiles were obtained, and the contributions of the individual signal intensities of each constituent to the total measured signal intensity were determined (range: 8.4−27.2%). The present results are important since the synthesis of AMPA is normally performed in buffered aqueous solution and not in the solid state. The present study also indicates that a maximum yield of the desired ammonium salt of 12-molybdophosphoric acid is achieved by stopping the solid-state reaction at ca. 350 °C. The combined spectroscopic and chemometric approach used in this contribution appears applicable to other solid-state synthetic studies in order to reveal more detailed time-dependent information on the species present.