Research
  Key Laboratories
  Research Divisions
  Research Interests
  Supporting System
  Achievements
  Research Progress
  Research Programs
  Technology Transfer
    Location: Home > Research > Research Progress

Researchers Find Uncommon Hypervalent Fluorooxosilicophosphate

Silicates show broad physical and chemical properties, such as ionic conductivity, ion-exchange, lasing, adsorbents, catalysts, owing to their structural diversity. However, a lot of known silicates only exhibit structural framework composed of four-coordinated silicon and thus the number of structural block is limited.

Recently, hypervalent silicon, that is penta- or hexa-coordinated silicon, is reported in a number of organic compounds and has attracted wide interests. In comparison, hypervalent silicon is still very rare in inorganic compounds.  

In a study published in Chemistry – An Asian Journal, a research team led by Prof. LUO Junhua and ZHAO Sangen from Fujian Institute of Research on the Structure of Matter(FJIRSM) of the Chinese Academy of Sciences, introduced F into silicophosphate system and successfully synthesized a new fluorooxosilicophosphate Na4Si2PO4F9 in closed glass tubes.  

The researchers found that Na4Si2PO4F9 is composed of two distinct hypervalent fluorooxosilicate species (trans-SiO2F4 and SiOF5), which are not reported in inorganic compounds.

Notably, the coexistence of two distinct anionic groups in one compound is somewhat conflicted with Pauling’s parsimony rule. Theoretical calculations were carried out by cooperation with the team led by Prof. LI Chunsen from FJIRSM. The result reveals that this non-strict parsimony is rationally acceptable.  

Besides, temperature-dependent conductivity measurements showed that Na4Si2PO4F9 is a promising solid ionic conductor with both a high conductivity of 4.0 × 10-5 ·cm-1 and a low active energy of about 53.1 KJ·mol-1 at 700 K.  

This study enriches the structural chemistry of silicates and may provide a new platform for solid ionic batteries.  

 

A new fluorooxosilicophosphate Na4Si2PO4F9 is synthesized by partial substitution of oxygen by flurine, showing two uncommon hypervalent fluorooxosilicate species (trans-SiO2F4 and SiOF5) and exhibiting a high conductivity and a low active energy.  (Image by Prof. LUO’s group) 

  

Contact:  

Prof. ZHAO Sangen

Fujian Institute of Research on the Structure of Matter

Chinese Academy of Sciences 

E-mail: zhaosangen@fjirsm.ac.cn  

  

  

  

 


Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences
Address: 155 Yangqiao Road West,Fuzhou,350002,P.R.China Tel: 0591-83714517 Fax: 0591-83714946 E-mail: fjirsm@fjirsm.ac.cn
Copyright @ 2000-2009 fjirsm. All rights reserved.