It looks passive to me, due to the structure to be + past participle. However, if I take Z as a doer of the verb locate and change it around as in Z locates X, I am very confused with the meaning which I feel different from that in the "passive" format. I need to explain this to my students.
- Anybody can ask a question
- Anybody can answer
- The best answers are voted up and rise to the top
Locate is a transitive verb and so can form a passive. The active
becomes, in the passive,
However, in the construction X is located in Y, the -ed form of the verb is a participial adjective acting as the complement of the verb be. The question of voice does not arise. No one, I imagine, would think of sentences such as I am tired, This problem is complicated or They were very pleased as being any kind of passive. So it is with sentences like Paris is located in France and The key was located in the second drawer on the left.
Huddleston and Pullum, authors of ‘The Cambridge Grammar of the English Language’ distinguish between the ‘adjectival passive’ and the ‘be-passive’. In the sentence ‘Paris is located in France’, ‘located’ is the former, but the sentence ‘The source of the river was located by the three travellers’ is the latter. They point out that the difference is that when the verb preceding an adjectival passive is ‘be’, it can be substituted by another verb. So, we can say ‘Paris remains located in France’, but in the second sentence, there is no alternative to ‘was’.
The Oxford Dictionary of English Grammar refers to this kind of construction as "pseudo-passive", i.e., it ".. neither has an active counterpart nor permits an agent." It contrasts pseudo-passives (which it also calls statal passives), where the verb to be is "arguably a copular verb," with true passives (actional passives), which can be converted to an active form with the agent as the subject.
Here's a good primer on the passive by Geoffrey Pullum, a contributor to Language Log and co-author of The Cambridge Grammar Of The English Language.
Most of the dictionaries have entry located as adjective with the meaning situated. In your example, there is adverbial complement in Y as in
To mention about passive, There must be "doer" in the sentence - at least hidden one we perceive. Sometimes this does not seem possible.
And probably that is the reason dictionaries take it as adjective. On the other hand, from the example below, it is clear that "located" is used as verb.
In my opinion, they are all sentences in passive voice.
I am tired because something / someone has been tiring me. Same for "They were very pleased"
Paris is located in France. It's a passive voice. The fact that it means that Paris is in France, does not exclude the fact that passive voice is being employed to convey this idea. Same for "situated".
As for "The problem is complicated", I would use "complex" to avoid this question whether it is a passive voice construction or not. Frequent use of this complicated as complex resulted in this type of phrase.