A Study on the Chemistry of the Rare Earth Elements

Citation preview

A STUDY ON THE CHEMISTRY OF THE RARE EARTH ELEMENTS

by A lex a n d er I* Popov

A d i s s e r t a t i o n s u b m itte d in p a r t i a l f u l f i l l m e n t o f th e r e ­ q u ire m e n ts f o r th e d e g re e o f D octor o f P h ilo so p h y in th e D epartm ent o f C h e m istry and C hem ical E n g in e e rin g , in th e G rad u ate C o lle g e o f th e S ta te U n iv e r s ity o f Iowa F e b r u a r y , 195$

ProQuest Number: 10666182

All rights reserved INFORMATION TO ALL USERS The quality o f this reproduction is d e p e n d e n t upon th e quality o f th e c o p y subm itted. In th e unlikely e v e n t that th e author did not sen d a c o m p le te manuscript and there are missing p a g e s, th e s e will b e n o ted . Also, if material had to b e rem oved , a n o te will in dicate th e deletion.

uest. ProQuest 10666182 Published by ProQuest LLC (2017). Copyright o f th e Dissertation is held by th e Author. All rights reserved. This work is p ro tected against unauthorized co p y in g under Title 17, United States C o d e Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106 - 1346

ACKNOWl£DGhENTS The a u th o r George G io c k le r , who

i s d e e p ly in d e b te d t o P r o f e s s o r s u g g e s te d t h i s p ro b le m , f o r h i s

c o n tin u e d i n t e r n e t and a s s i s t a n c e .

P r o f e s s o r G lo c k ie r ’ s

in s p i r i n g e n th u sia s m d id more to f u r t h e r t h i s s tu d y th a n can be e a s i l y e x p re s se d * I t i s a l s o a p le a s u r e to acknow ledge th e f r i e n d l y h e lp and s u g g e s tio n s o f f e r e d by many f a c u l t y members and g ra d u a te

s t u d e n t s , in p a r t i c u l a r Dr# L o th ro p

S m ith , D r, R o b e rt B u c k le s , Dr# George M a tla c k .

F D

X Li

Sherman R a b ld ea u , and D r.

iii

. The r a r e e a r t h s p e r p le x a s in o a r r e s e a r c h e s , b a f f l e u s in o u r s p e c u l a t i o n s , and h a u n t u s in o u r v e r y d ream s.

They s t r e t c h l i k e

an unimown se a b e f o r e u s , m ocking, m y s tif y in g , and murm uring s tr a n g e r e v e l a t i o n s and p o s s i b i l i t i e s . *. n

S i r W illia m C rookes

iV FOREWORD T h is s tu d y i s on© o f a s e r i e s c a r r i e d o u t in th e s e l a b o r a t o r i e s , u n d e r th e d i r e c t i o n o f P r o f e s s o r George O lo c k le r , on th e valency s t a t e s ' o f th e r a r e e a r t h

e le m e n ts .

P o ta r o g ra p h ic i n v e s t i g a t i o n s w ere made o f

praseodym ium { ! ) , neodymium (2 ) , g a d o lin iu m (%) 9 and sam arium (i|.) *

I t was fo u n d t h a t th e e v id e n c e g iv e n by

tfoddack and Brukl (5 ) f o r th e r e d u c t io n o f the t r i v a l e n t

io n s o f th e f i r s t th r e e e le m e n ts a t th e d ro p p in g m ercu ry e l e c t r o d e was erroneous; sa m a ric io n Sm *^ on th e o th e r hand was re d u c e d to samarous io n Sm4*% R ab ld eau and G lo c k le r ( 6 ) have a l s o in v e s t i g a t e d th e c h e m ic a l and m a g n e tic p r o p e r t i e s o f praseodym ium and have shown t h a t th e two h ig h e r o x id e s ,

and PrO^ b o th

c o n t a in th e e le m e n t in te tr a v & le n t s t a t e , r a t h e r th a n p e n ia v a ie n t a s was p o s tu l a te d by some of th e e a r l i e r I n v e s t i g a t o r s (7 # 8 ) . The w ork r e p o r te d in t h i s d i s s e r t a t i o n c o n c e rn s i t s e l f w ith th e s tu d y o f th e v a le n c y s t a t e s o f neodymium a n d , in p a r t i c u l a r , th e p o s s i b i l i t y o f fo rm a tio n o f th e h ig h e r o x id e s . 4

The c h e m is try o f th e r a r e e a r t h s i s Im p o rta n t b e c a u se many o f them a r e p r o d u c ts o f n u c le a r f i s s i o n .

V

TABLE OF CONTENTS

page PART 1 T h e o r e tic a l in tr o d u c tio n *

1

C h a p te r I

II 111 2V

The R are A, B* C.

E a r th E le m e n ts ............... 4 C l a s s i f i c a t i o n * . . * . ............ , . » #fil H is to ric a l* .......... ,.j S e p a r a tio n * .......... .*..*7

V alen cy and E l e c t r o n i c S tr u c tu r e o f th e R are E a r th E le m e n ts ..................* . . * * . , 1 5 The L a n th a n id e s and th e A c tin id e s * Review on th e H ig h er O x id a tio n S t a t e s o f Neodymium* **

.

2

6

* ** * J | 1

PART I I E x p e rim e n ta l W ork,* ..........

. . . . . . .................

C h a p ter V

P r e p a r a tio n o f th e Neodymium Com pounds.* * * ,,k!i A, O x a l a t e ........................................ .hL B, Oxide* » * * • . . . , . * « » . , .......... *1|,5 C* F lu o rid e * .......... *1|6 D, A n a ly s is o f th e F l u o r i d e . J47

VI

A ttem p ted O x id a tio n s o f th e Neodymium*. . . . . .ij.9 A, F u sio n w ith O x id is in g A g e n ts * . 49 Armon ium n I i r a t e ...........* .if.9 ............. .5 $ Ammonium p e r s u l f a t e Sodium c h l o r a t e .................. 51 B* O x id a tio n w i t h O x y g e n * * § 1 C, A n a ly s is o f “A c tiv e *1 Oxygen in B lack Praseodymium O x id e. • . . .......... 56

Vi TABLE Of CONTENTS ( C o n t M )

page

C h a p te r V II

F lu o r i n a ti o n o f Neodymium and Praseodym ium Compounds* . . . . . . . . . . .............60 A* I n tr o d u c tio n * . . . . . . . . . .................. . . . „ 6 0 B, C h lo rin e T r i f l u o r i d e . * .........., 6 l C. Bromine T r i f l u o r i d e ...........65 D is c u s s io n and C o n c lu s io n . B ib 1 io g r a p h y .

............*.................

............................. .6 0 *69

Vii

TABLE OF FIGURES page F ig u re 1

H i s t o r i c a l Scheme o f th e D isc o v ery o f th e R are E a r t h s .................................. ..

•

2

Anomalous V a le n c ie s o f th e Rare E a r th s a c c o rd in g to P e a r s e ............

A6

5

Anomalous V a le n c ie s o f th e Rare E a r th s

A9

I4.

The F l u o r i n a t i o n A p p a ra tu s

............. .

m6

.63

v lil TABLE OF TABLES

page T ab le 1 'E le c tr o n ic Conf Ig tx ra tio n and th e T ern Symbol o f th e H e u tr a l R are E a r th Atoms in th e Ground S ta te a c c o rd in g to Hund ( 5 W ...... II

III

IV

21

E l e c t r o n i c C o n f ig u r a tio n and Lowest Terms o f th e R are E ar th E lam en ts {5 6 ) .............. «*«................ .25 P o s s ib le E l e c t r o n i c Configuration f o r E le n e n ts No* 86 to 1 1 0 * . » » » . . « • . • * * • • «

* * * **27

Known V alen cy S t a t e s o f th e Heavy E le m e n ts*

V E l e c t r o n i c Configuration and Term Symbols o f th e Heavy E l a m e n t

*J2

s

*3h

VI

I o n ic R a d ii o f th e Heavy E lem ents and th© ........................................... ............... ..**37 Rare E a r th s {6 9 )

V II

Com btisiion o f Neodymium O x a la te in Oxygen*.* * ..* * 5 5

VIII

D eh y d ratio n o f th e B a sic Neodymium O x id e* ********57

IX

”Ac l i v e Oxygen” in Praseodymium O xides* «• • • # « * • • » 5 9

I

fart

I

THEORETICAL IHTRODUCTIOH

Chapter I THE M M EARTH ELEMENTS

Th© term wrare earths* a n a l l y applies to four­ teen elements of atomic numbers $8 to 71 Inclusive, that is: Cerium

Terbium

Praseodymium

Dysprosium

Neodymium

Holmium

Promethium

Erbium

Samarium

Thulium

Europium

Ytterbium

Gadolinium

Lutecium

However, there Is some difference of opinion on this sub­ ject and some authors prefer to include within the group also lanthanum, yttrium and even scandium as these three

2

©hew c o n s id e r a b le c h e m ic a l re se m b la n c e to th e e le m e n ts named, and a r e

m m tty

found in th e s w

m in e ra ls .

I t I s Indeed d i f f i c u l t t o d e c id e w here th e l i n e sh e a Id be drawn*

However*, from th e p a i n t o f v iew o f th e

e l e c t r o n i c s t r u c t u r e i t seem s l o g i c a l to l i m i t th e u se o f th e te rm t o th e f i r s t f o u r te e n e le m e n ts* The c u r io u s p r o p e r t i e s o f th e r a r e e a r t h s and th e g r e a t s i m i l a r i t i e s in t h e i r chemical and p h y s ic a l p r o p e r t i e s s e t them a p a r t from o t h e r e le m e n ts .

U n t i l r e c e n t l y th e y

d id n o t seem to f i t I n to th e p e r i o d i c sy stem In s p i t e o f many a tte m p ts t o f i n d a p la c e f o r them*

W ith th e d is c o v e r y

o f th e tra n s u ra n iu m e le m e n ts c o n s id e r a b le p r o g r e s s in t h i s d i r e c t i o n h as b ee n made*

One o f th e m o st r e c e n t p e r io d ic

c h a r t s containing th e r a r e e a r t h e le m e n ts and show ing t h e i r r e l a t i o n to th e tra n s u ra n iu m e le m e n ts I s g iv e n by Clockler ( 9 )*

An e x c e l l e n t re v ie w o f some o f th e e a r l i e r a tte m p ts

was co m p iled by E s ie e ( 1 0 ) . The r a r e e a r t h s c a n be s u b d iv id e d i n t o two o r th r e e g ro u p s . a)

One c l a s s i f i c a t i o n d iv id e s them in to *

Cerium G roup.** e le m e n ts from c e riu m to eu ro p iu m , V ttrlu m G ro u p .-» e le m e n ts from g a d o lin iu m t o lutee Itmu

5

A n o th e r c l a s s i f i c a t i o n 1st a)

C ar lam jgJgSE*^

ts from c e riu m t o eu ro p iu m ,

b)

fe rb iu m G roup** g ad o lin iu m * te rb iu m and dysprosium *

c)

y t t r i u m G roup** e ls m e n is from holmium to lu te c iu m . The c l a s s i f i c a t i o n s a r e somewhat a r b i t r a r y and

a r e b ased on th e o c c u rre n c e o f e le m e n ts In n a tu r e and on th e s o l u b i l i t y o f t h e i r d o u b le s u l f a t e s *

The h i s t o r y o f th e r a r e e a r t h e le m e n ts I s c h a r ­ a c t e r i s e d by th e unusual d i f f i c u l t i e s e n c o u n te re d by th e e a r l y i n v e s t i g a t o r s in th e s e p a r a tio n and i d e n t i f i c a t i o n o f th e v a r io u s members o f th e group*

One h u ndred and f i f t y

y e a r s o f p e r s i s t e n t e f f o r t w ere need ed t o b r in g a sem blance o f o r d e r i n t o t h i s f a s c i n a t i n g c h a p te r o f c h e m is tr y , b u t ev en now t h e r e a r e la r g e gaps in th e Knowledge o f some o f t h e i r c h e m ic a l and p h y s ic a l p r o p e r t i e s . In 179^ th e F in n is h c h e m ist Gad© 1 in d is c o v e re d a new o x id e , ny t t r i a , M In a m in e ra l found by a Sw edish o f f i c e r , I t . A rrh e n iu s* n e a r a sm a ll town by th e name o f Y ile r b y In Sweden*

A few y e a r s l a t e r a German ch em ist*

h Klaproth, while working m

a mineral, cerlte, discovered

another oxide which was subsequently called *cerla** the complex natttre of these

nm oxide#,

or

^earths* as they were called,, was recognised In 181*5 following the brilliant work of Carl Moeander, friend and collaborator of Bersetfus*

IfoWMde*

succeeded In splitting ceria into three

oxides, ceria proper, laniimaa and didymla, while the fractionation of yttria yielded the tree yttria, erbia and terbisu

It Is of interest to note that the last two names

were confused m m t i m

later and were Interchanged *

It soon became evident that most of these new earths were, In their tarn, complex mixtures*

In 18?8 de

tferfgnec separated ytterbi* from erbla, and In the follow­ ing year Ni'lson isolated scandia from ytterbisu Erbia was still farther resolved by Clave into three constituents, erbia, hotels and thulla.

Lecoc de

Bolsbaudran isolated from didymla a new earth, samarSa, which on further fractionation yielded gadolinia*

He also

separated from ho tela a new element which he called

d y s p ra x ia * In 1901 Demarc&y made a series of fractionations on Boisbaudran’s samarIa and discovered a new earth which

5

tm c a lle d europla and * tm ym t * la te r Urbain separated the known y tte r b la Into lu ie e la and y ite f b ia proper* Figure I gtw#i a schematic Illu stra tio n of the gradual separation of the complex, mixtures Into individual e lem e n ts# ' When the work of Masely had settled the number of possible chemical elements between hydrogen and uranium, It became evident that element Ho*

6l

was still to be found,

Simultaneous claims of Its discovery were made

Yfttem

by

ifarris,

and Hopkins (11) mi the University of Illinois and

by Holla and Fernandes (II) at the University of Florence* Subsequent work by Hodd&ck and others (15# lif-) failed to prove the validity of these claims and It Is generally accepted now that the element Ho. 6i was produced for the first time by the fission of uranium and by the neutron bombardment of neodymium (15# 16# l?# IS# 1 9 )*

‘Hie credit

for its discovery belongs to liarinsky, Olcndcnin and Coryell who have first Isolated and chemically Identified the new element (20) *

* p m m ihfum*1 which Chemical Union.

They have proposed for It the

mm

was accepted by the International

It seems fairly well established that

promethium does not occur in nature.

More than fo rty o th er elements belonging to the rare e a rth group were claimed to have been discovered a t

6

ce CERIA

Li

\

hi±i o

0 X O

o E arth s

~CJ

-o

of

0- u

the

Hare

I-

V alen cies

oo

£

Q_

Anomalous