Powder Diffraction Standards for Niobium Pentoxide and Tantalum Pentoxide L. K. FREVEL and H. W. RlNN The Dow Chemical Co., Midland, Mich. \ re-examination of powder diffraction data for tantalum pentoxide has disclosed that niobium and tantalum were the chief constituents of the commercial sample used i n the original investigation. New data have been obtained with tantalum pentoxide prepared by direct oxidation of tantalum metal and w i t h a commercial sample of niobium pentoxide.
I
4 1953 H. 0. Spauscliuc informed the authors that standard
pattern 905 ( 4 )cliffered from the powder data of the tantalum pentoxide samples secured by him. T h e powder specimen of t:intalum pent,oxide used for pattern 905 was obtained from 1-imer and Amend and was labeled “Tantalum Pentoxide, . k i d T:intalic Anhj-dride. c.P.” d rerun of the original saniple confirmed t h e published diffraction data. However, a micror.oinblwtion of the s:inie ponder sample showed that i t lost S.5V0 I)!- weight and contained 2.33% carbon and O . i O % hydrogen. Ppettroscopic :tnalyqis of the ignited sample (giving t h e same powder pattern as the original material) shoxed tantalum and nioliium as chief constit,uents and silicon, aluminum, and titanium :I: minor impurities. I n view of these findings and the suhsequent literatiire data (1-3, 5 , e ) ,the author.; prepared tantalum pentoytide by the direct osidation of C.P. tantalum nietnl pur-
Table I.
~
clinsed from the Fansteel ,\letallurgical Corp. T h e weight increase due to osidation of the metal wa8 determined: Iii
111
oxygen at 800” ‘2-21 92% (22.1170 theor! :iir a t 750” C.-21.97% (22.11% theoryI
Table 11. Powder Diffraction Pattern of Pseudohexagonal Niobium Pentoxidea a, .I. [t‘nr1 ( I I.), fI/ILi, 00 1
0.00 1 .on 0.39 0 18 0 .d o 0.21
inn
101 002 1i n in2 111 200 201 112 003 202 103
0.1.7
0.08 0.07 0 . 11)
__~~_____
~
~
Powder Diffraction Data for Siobiunl Pentoxide and Tantalunl Pentoxide’
d , 1.
[hkil 121 :02
5 . l!A
5 29
0.03
in1
4.2u2
0.01
040
3,885
1 00
113
3.4%
0.n:
3.333
O.O.i
(im: 3.924 :i , 4 9 2
Tal06 _ d , A. 1 ,‘I 1
212 211 181 i4n 141
zoo
3.146
3.120
1 ,011
3.093
0.43
2,984 2 , Slii)
0 I)? 0.02
.
XbzOs d , -1,
2.30 1
I I1
TazOa d , .I. I I:
0.02
. 40
2,456
I)
2.427
n . 1s
2 533
0.04
2.447
0 $32
2.420
0.39
L’,:372
004
2.101
0.0:
0.02 0.07 0 24 0.01 n , 07 0 .l i 0.20 0.01
L’1 . 0924 3
0.211 0 n:(H
1 830 1 800 i 76.7 I fi78 1.Gi 1.~31
0 23
ni
1 1306
203
3 .os’;
003 izin) (213) 042 151 I22
10.04
02:3
- .-.,-,
0
2 121
2:i:j
-,.I
2x0 130 033
148 132 242 241
2 ,7 x
2.048
I)
0 1s 0.1.5
0 I! I) 0 ; 0 08 0 03 0.01
I 577 1 349 1497 1 402 1 440 1.405 1 381i
0.12
n
n4
n
01
0 31.)
n
04 0 011 n 04 0 04
nil:
