Author Topic: rare earth ultraphosphate standards  (Read 623 times)

crystalgrower

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rare earth ultraphosphate standards
« on: July 03, 2018, 03:46:12 pm »
I am starting a new thread to clarify information under heading "standards database"

The Chinese Micro Analytical Society (CMAS) sold REEP5O14 crystals to the late Dr. Chuck Garber sometime around the year 2000.  These were mounted into an SPI exclusive product.  No references to syntheses was provided. Stoichiometric values were included in SPI documents.

In 2005 Dr John Rucklidge the founder of Astimex Scientific Limited commissioned me to grow these crystals larger if possible.  The full suite was released for validation in mid 2009.  Both Astimex Scientific and SPI Supplies began selling the Astimex loose crystals and mounts at the beginning of 2010. The price for Astimex mounts dropped about 25% from mounts with China crystals.

In 2012 I started my own business to manufacture the RP5O14 using a different process that increased yield for the LREE-P5O14.  The brand name Geo Chemicals was not registered.

I have never had any connection to Astimex Standards Ltd that took over stocks and processes from Astimex Scientific in March 2013. Some of the 2009 Astimex LREE-P5O14 should have run out by 2014.


Most important information:

--these three sources were all free of Pb and all other reagent or flux contaminants.   Each batch of 2009 Astimex crystals was assayed for contaminants by batch XRF.  They were run by EPMA-EDX against mounted China crystals but not the Pb fluxed-RPO4. 

The Astimex crystals were the high-temperature high-symmetry form with no  twinning or ferroelastic issues.  These crystals are not optimal for lasers.

The new crystals had a higher yield because I chose a different starting material.  It turned out that this starting material was difficult to prepare but could be done in parallel batches.  The syntheses were then straightforward with a minimum of waste.

Pricing:

I do not know what the current Astimex Standards price for loose grains is.  I do not know what the provenance of any Astimex product  is.  They are called "phosphate" on Astimex webpages although the formula is shown as RP5O14.

Speaking only for my self-funded work under the Geo Chemicals brand:

I only offer loose crystals of RP5O14,  at CDN $30 each.  My documentation is more detailed than current online information from any source.  Please contact me offline.








« Last Edit: July 04, 2018, 11:29:00 am by crystalgrower »

crystalgrower

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Re: rare earth ultraphosphate standards
« Reply #1 on: July 14, 2018, 01:32:01 pm »
I have attached a recent report on the use of SDD for good EDS quantitative results. 

This should provide an objective valuation of RP5O14 for EPMA.


Probeman

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Re: rare earth ultraphosphate standards
« Reply #2 on: July 14, 2018, 01:58:51 pm »
This is an excellent paper and demonstrates what one can accomplish with EDS, when one takes the same care and effort that are typically employed with WDS methods.  E.g., there is no such thing as "standardless WDS"!  :)
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